*{
    margin: 0;
    padding: 0; 
}
body{
    display: flex;
    height: 100vh;/*vh means view height*/
    background: #4c4c4c url("https://unsplash.it/1500/900?image=1021");
    justify-content: center;
    align-items: center;
}
.wrapper{
   display: flex; /*flex means flex box 弹性布局*/
   width: 850px;
}
.flex{
    width: 765px;
    height: 430px;
}

.speed{
    flex: 1;
    display: inline-block;
    background-color: #fff;
    margin: 10px;
    border-radius: 50px;
    overflow: hidden;
}
.speed-bar{
  display: flex;
  width: 100%;
  height: 10%;
  background: linear-gradient(to bottom,#2376ae 0%,#c16ecf 100%);
  justify-content: center;
  align-items: center;
  color: #fff;
}
